A method and a device for measuring the temperature of substrates to be coated in a vacuum coating apparatus are described hereafter.
Coating substrates in vacuum coating apparatuses, e.g., by sputtering, is known, the layer typically not exceeding a thickness of several micrometers, and a plurality of substrates being moved past a stationary coating source in sequence. As a function of the selected method and the coating material used, very high temperatures may occur during the coating process and act on the substrate to be coated. For example, temperatures of up to 600° C. may occur during the coating of glass substrates with molybdenum. To ensure high quality of the coating and for processing control, it is necessary to know the actual temperature of the substrates. The temperature measurement within the vacuum coating apparatus required for this purpose is frequently connected with difficulties, however. One problem, for example, is that temperature sensors which are attached on the surface of the substrate to be coated may unintentionally also be coated. In addition, the measured values are corrupted. One cause of this is the unintentional coating of the sensor itself, as already noted. A further cause may be seen in that both the temperature sensor itself and also the adhesive used for fastening it on the surface of the substrate generally absorb the existing heat radiation to a different extent than the substrate itself
A method for producing a target for a sputter magnetron is known from DE 699 29 971 T2, in which a layer having a thickness of at least 3 mm is implemented at atmospheric pressure on the substrate by flame or plasma spraying, a tubular substrate being situated stationary in relation to the effective area of the spray gun and rotating around its longitudinal axis. A temperature measurement is performed in the interior of the tubular substrate.
Devices for depositing thin layers on the substrate by a CVD process, i.e., without a coating source, are known from DE 102 07 901 A1 and U.S. Pat. No. 6,284,048 B1, in which wafers are structured in a reactive gas atmosphere, one or more wafers being situated on a substrate holder situated so it is rotatable in the reactor housing and a temperature measurement being performed on the rear of the wafer.
For the coating of substrates in vacuum coating apparatuses, e.g., by sputtering, a plurality of substrates being moved past a stationary coating source in sequence, there is a need for a method for temperature measurement on the substrates to be coated, in which the actual temperature of the substrates is reliably ascertained and unintentional coating of the temperature sensor is avoided. Furthermore, a vacuum coating apparatus which is implemented to perform the suggested method is required.